1. Field of the Invention
The present invention relates to a multifunction system that provides; (1) local distribution company tailored instructions for performing identified covered tasks; (2) training programs foe teaching operators to correctly perform covered tasks; (3) testing and evaluation programs to determine the qualification of operators to perform covered tasks and (4) detailed records of performed tasks.
2. Description of the Prior Art
Mechanical, heat fused (conventional/electric heat weldable) fittings formed of thermoplastic material have been in commercial use for many years. The most recent are electro-fusion fittings include in-line couplings, saddles and socket fittings. Such fittings generally have an electric resistance heating coil or an electric element positioned adjacent the interior surface of the fitting which is to be fusion-welded to one or more other thermoplastic members. The electric resistance heating element usually is in the form of a coil resistance wire embedded in the thermoplastic material of the fitting. The fitting typically includes external electric contacts that communicate with the resistance wire. By means of conductors extending from electrical contacts, electrical energy can be applied to the electrical coils. As current flows through the electric resistance wire, heat is generated that raises the temperature of the mating surfaces of the fitting and adjacent plastic element to which the fitting is to be fused. When the temperature of the mating surfaces both reach a molten state thermoplastic fusion occurs. When the molten surfaces cool, the components, that is a fitting plus a second element such as a length of pipe, are integrally joined.
Heat weldable thermoplastic fittings that employ electrical energy are described in U.S. Pat. Nos. 4,147,926 and 4,349,219. These patents are incorporated in this application by reference.
The quality of the weld which results from electro-fusion is primarily dependent on the correct quantity of electric power supplied to the heating element or elements of the fitting. If too little electric power is supplied, too little heating takes place and an inadequate low strength weld results. If too much electric power is supplied, the fitting and the plastic member to which the fitting is welded can be deformed so that a good weld does not result. Other factors that effect the quality of an electro-fusion procedure include heating element abnormalities that is, short circuits, poor alignment between the fitting and the plastic pipe or plastic member to which the fitting is being welded, poor contact between the surfaces to be fused, and so forth.
Others have designed and made commercially available control systems for supplying electric power to electric heat weldable thermoplastic fittings. When electro-fusion products first came on the market, they were typically controlled manually by an operator. That is, the operator manually turned on the supply of power to the fitting and turned it off, depending on experience and visual observations of the fittings as to the proper length of time to apply energy to the fitting to obtain successful fusion. At the present time, control apparatus has been developed so that the operator programs the apparatus to supply a pre-determined quantity of electric energy to the heating element or elements of the fitting in accordance with the shape, size and character of the fitting. In addition, others have devised fittings for electro-fusion that have heat sensors formed when the fitting is manufactured. The sensors detect heat produced by the heating element or elements to thereby determine when the mating surfaces to be fused have reached molten temperature. For background information relating to electro-fusion devices that have integral heat sensors, reference may be had to U.S. Pat. No. 4,486,650 that issued on Dec. 4, 1984. This patent is incorporated herein by reference.
When polyethylene plastic pipe was first introduced to the commercial market it was used primarily as conduits for water, either water under pressure or waste water. As experience has been gained in the quality control of installation of thermoplastic pipe and as the quality of thermoplastic pipe and fittings have improved, thermoplastic pipe is now also frequently employed for transmitting gas, particularly natural gas distribution systems to residential and commercial customers. Since natural gas is combustible and highly explosive, the Department of Transportation (DOT) has established regulations regarding the use of thermoplastic pipe for natural gas and has established safety control procedures regulating the construction of natural gas systems. These procedures include regulations regarding joining procedures including mechanical and heat fusion (conventional/electro) for connecting polyethylene fittings to plastic pipe. Further, DOT has mandated certain training and qualification requirements for those authorized to perform the covered task of joining procedure of fittings and plastic pipe.
For further background information relating to electro-fusion of thermoplastic pipe and fittings, reference may be had to the following previously issued patents:
PATENT NO.INVENTORTITLE4,486,650Bridgstock et al.Electro-Fusion Fitting andControl Apparatus Therefor4,684,789EgglestonThermoplastic Fitting ElectricWelding Method andApparatus4,795,877Bridgstock et al.Fault Detecting Device forWelded Pipe Joints4,947,012MinarovicElectro-fusion Marker4,994,655Handa et al.Electro-Fusion Joint5,116,082Handa et al.Electro-fusion of Electro-fusion Joint, Method ofConfirming State of Fusionand Fusion Joint Suitable forUse int eh Methods5,130,518MerleElectric Welding Apparatusfor Automatically WeldingHeating Coil Fittings5,138,136Moreau et al.Method, Circuit andApparatus for Supplying anElectrical Current to aResistive Heating Element5,170,042BunnIdentification of Electro-Fusion Fittings5,228,186Brettell et al.Method of ManufacturingElectro-Fusion Fittings5,462,314Goto et al.Electro-Fusion Fitting Havinga Solid Embedded Heaterwith PerpendicularProjections5,500,510KumagaiMethod of AutomaticallyControlling the FusionProcess BetweenThermoplastic Articles5,779,843Kumagai et al.Method of Fusion WeldingResin Articles Difficult toMelt5,951,902Goodman et al.Method and Apparatus forElectrofusing ThermoplasticJP 7-260082JP 9-292084EP 0 082 451Thalmann et al.Process and Turn Out toWeld from Line ItemsEP 0 299 833Nussbaum et al.Process and Machine for theWelding between them ofPlastic Parts Comprising aWinding IntegerCH 668 741SturmProcess and Device to WeldPlastic Shaped Parts